The present invention relates to a unit for polishing bevels on the edges of glass plates, particularly on numeric-control machines.
It is known that during the manufacture of glass plates multiple treatments are performed in succession at the edge of the plate, using different grinders to produce in succession the grinding or shaping of the bevel and ending with the polishing operation.
In conventional treatment methods, the various devices are preset to perform a specific treatment; in particular, currently commercially available machines form a partly polished edge or bevel with polishing grinders which use the same water used for grinding.
Actual polishing is then performed on other machines, using a mix of water and cerium oxide, which must be present in very specific percentages.
With these machines it is possible to recuperate the mix of cerium oxide and water, which is relatively expensive, so as to reuse, in practice, the same mix in a closed cycle.
Automatic or numeric-control machines used for the treatment of glass plates can conceptually perform, on a single device, the automatic succession of the various operations, since the treatment head is capable of automatically replacing the grinder, thus allowing to perform all the required treatment steps.
However, with this kind of device there is the problem of polishing, since the mix of water and cerium oxide used for polishing cannot be mixed with the water used for grinding, both because the mixing percentages would be altered and because one would use a mix contaminated by glass powder, which would produce scratches on the glass during polishing.
The other solution, i.e., to use a mixture of cerium oxide and water which is not recycled but disposed, is not practicable since cerium oxide has a relatively high cost.
Accordingly, the principle of the numeric-control machine is severely penalized; said machine should inherently be able to produce a perfectly finished product, but in practice it requires the transfer of the product to another machine to perform the final polishing operations.